Electrically driven vehicle



Feb. 20, 1934. s. s. GUY ET AL ELECTRICALLY DRIVEN VEHICLE OriginalFiled Ma 29, 1930 2 Sheets-Sheet 1 Feb. 20, 1934. s. s. GUY ET ALELEGTRICALLY DRIVEN VEHICLE 2 Sheets-Sheet 2 Original Filed May 29, 1930INVENTORS W a. "1% 47% Z. #W

Patented Feb. 20, 1934 UNITED STATES PATENT OFFICE 1,948,376ELECTRICALLY DRIVEN VEHICLE Sydney Slater Guy, Wolverhampton, andWilliam Arthur Stevens, Maidstone, England Serial No. 624,266

4 Claims.

This application is filed as a division of our prior application Ser.No. 457,304, filed May 29, 1930 for Electrically driven vehicles.

This invention relates to electrically driven vehicles in which thedynamo-electric machinesareof" the compound wound or regenerative typeand in which the series and shunt field windings have-in seriestherewith resistances that can be u progressively cut in or out ofcircuit by a controller drum actuated by a spring loaded power pedal.

The object of the present invention is to provide means whereby thecontrol of the system m for thepurposes of regeneration is securedautomatically and-independently of the angular position of thecontroller drum so that if, when the vehicle is descending a gradient ortravelling at speed, and the driver takes his foot off the power pedaland the controller drum in consequence returns to the off position underthe influence of the pedal spring, the circuits maintaining regenerationare automatically closed, the machine then commencing to return currentback to supply and exerting a braking eii'ect on the'vehicle-until suchtime as the speed of'the latter is so-reduced that the voltage of thegenerated current falls below that of supply.

A further object of the invention isto arrange the electricalconnections so that when the machine commences to act as a generator thecurrent is automatically diverted from the series field Winding.

Meansare also provided whereby the circuits can be automatically brokenimmediately the mechanical brakes are applied so that it will beimpossible for" the driver to apply power and braking at the same time.

Inthe accompanying drawings,

Figure 1 illustrates, diagrammatically, one method of keeping thecircuits closed during regeneration.

Flgure 2 illustrates, diagrammatically, an alternative method ofmaintaining the circuits ,5 closed during regeneration.

' Figure, 3'shows, also diagrammatically, a further modification. of theinvention in which the current is automatically diverted from theseries, field, winding during regeneration.

I Referring to the drawings, 1 is the armature of. a compound-wounddynamo-electric machine, theseries and shunt field windings 2, 3 ofwhich have: variable resistances land which arecon- 55 nected irrseriestherewith respectively and are controlled by. a starting and. speedchanging. re-

sistance controller drum 22 operated by' a power pedal. The circuit iscompleted through contactors' 16-16 which are respectively connectedwith stationary contacts -20 in the known manner.

The arrangement shown in Figure 1 involves the provision of a polarizedcontactor 50, the heavy winding 51 of which is inserted in' circuit withthe end of the series winding 2 nearest armature 1, Whilst the fine wirecoil 52 is connected either in shunt or in series with the shuntfieldwinding 3. The top contact of the switch is connected with the lead fromthe series field winding 2 to the series resistance 4', w whilst theswitch arm is connected to trolley pole 6.

When the vehicle is travelling at speed and the power pedal is released,the machine commences to act as a generator and closes the contactor 750 by the voltage generated through the shunt field path. This completesthe circuit through the armature of the machine and the series fieldWinding across the supply poles 6 and 7. When, in consequence of theresulting electrical braking effect, the speed of the vehicle is reducedto such an extent that the voltage at the terminals of: the machinefalls below that of the line the contactor automatically opens andbreaks the said circuit.

Another arrangement whereby the circuits 0! electrically driven vehiclescapable of regeneration are automatically kept closed during the wholetime the dynamoelectric machine is acting as a generator, is shown inFigure 2 and in'- volves the provision of a reverse current relay havingtwo windings 29, 29 connected in circuit with. the series and shuntwindings 2, 3 respectively. In this case the contact 30 is connectedwith the exciting coil 58 of a main contactor switch 58. Associated withthis switch and closing at the same time isan auxiliary switch 60,oneterminal 60 of which is connected with trolley pole? whilst the otheris connected with the stationary contact 20*.

When the dynamo-electric machine regenerates, the armature 30 of therelay closes its contact thereby short-circuiting the series winding 2through themain cont'actor switch 58 and at the same time completing thecircuit between trolley polev 7 and contact 20 by" way of the auxiliaryswitch 60, thus maintaining energized theicircuit already made from thesame polarity by drum 22. The contactor switch 16, associated withcontact 20 is mechanically connected toan auxiliary'switch 16 whichwillclose at the same time as contactor switch 16*. The circuit fromcontact 2O is continued to contact 20 by way of this auxiliary switchwhen contactor switch 16 closes, thereby maintaining energized thecircuit to the windings of contactors 16 and 16 and the main circuit totrolley pole 6.

W heri the dynamo-electric machine is running at speed with the controlsin the position for forward running, and the power pedal is allowed tocome back, the current in the shunt field winding 3 is increased so thatthe voltage of the dynamo-electric machine becomes higher than that ofthe line. Regeneration will then take place and the reverse currentrelay will complete the circuit from circuit 18 to contact 2O by way ofthe contactor and thence, by way of the auxiliary switch 16 to contact20, thus keeping the supplementary resistance 32 short-circuited andthereby maintaining the shunt field at full strength.

In the event of the power pedal being allowed to come back to its ,oiTposition, contactor switches 16*, 16 and 16 will remain closed until thevehicle slows down to the speed at which regeneration ceases. Thereverse current relay will now open its circuit and the contactorswitches last mentioned will open, cutting off the electric power fromthe dynamo-electric machine.

For the purpose of stopping the vehicle on a down gradient or on thelevel, when regeneration is taking place a switch 18*- is provided inthe exciting circuit 18. This switch is operated by ,the brake pedal notshown, being closed when the pedal is in its back or off position.

The action of applying the brake pedal immediately opens this switchwhich breaks the exciting circuit to all contactors, which will open andcut off all external power from the dynamo-electric machine.

There may be mechanically connected with the main contactor 58 a secondauxiliary switch 59 adapted, when the relay closes its circuit duringregeneration, to open and introduce a resistance 59 into the lightingcircuit 61.

Any suitable type of reverse current relay may be used in this inventionand the armature may be a permanent magnet with or without an excitingcoil.

cally cut out of circuit, so that the field maintained by the shuntwinding 3 is not weakened by the demagnetizing effect of the reversecurrent through the series winding, which otherwise, would have takenplace.

For this purpose a polarized relay is employed the heavy winding '70 ofwhich is inserted in circuit with the end of the series winding 2nearest the armature 1 and carries a current which varies in directionof flow accordingly as the dynamo-electric machine is acting as agenerator or as a motor. The other winding '71, in which the fiow ofcurrent is unidirectional, is connected in series with the shunt winding3, or, alternatively, may be of high resistance and connected in shuntwith the shunt winding. The armature '72 of this relay will close itscircuit when the machine becomes a generator and open its circuit whenthe machine becomes a motor.

A main contactor switch 73, actuated by the relay and closing at thesame time, has one terminal electrically connected with the main supplyfrom trolley pole 6, and the other terminal connected to the junctionbetween the heavy winding '70 of the polarized relay and the seriesfield winding 2. By means of this arrangement it will be seen that theheavy winding of the polarized relay will remain in circuit with thearmature of the dynamo-electric machine when the main contactor switch73 is closed and the machine continues to regenerate.

For the purpose of keeping the supplementary shunt resistance 32short-circuited and thereby ensuring the maximum field strength set upby the shunt winding 3, an auxiliary switch 74 is provided. This switchis linked to the main contactor switch 73 and arranged to close at thesame time. One contact of the auxiliary switch is electrically connectedto trolley pole 7 and the other contact to the stationary contact 20.The auxiliary switch when closed will therefore complete the circuitbetween trolley pole 7 and the contact 20 which will then have the samepolarity as the controller segment 21 when the latter is in contact withthe fixed contact 20 and will thus maintain the excitation of the twocontactors 16, 16, which are connected in series, and keep them closed.When the machine is motoring, the auxiliary switch 74 will beautomatically opened to break its circuit by the action of the maincontactor switch '73.

Alternatively, instead of the polarized switch '72 acting as a relay itcan be used as a main switch, completing the circuit of the armatureduring regeneration in the way already described, and the auxiliaryswitch 74 can be linked to the polarized main switch so that it can openand close at the same time and complete the circuit to stationarycontact 20 in the same way as it would if linked to the contactor switch'13- Means are preferably provided whereby the exciting circuit of themain contactor 73 can be broken in the event of any failure 01 the relayto function properly. For this purpose it is proposed to provide therelay circuit with a safety switch '75 adapted for operation by themechanical brakes, said switch normally remaining closed so long as thebrake is in the ofi position but opening immediately the brake pedal isdepressed.

We claim,

1. In an electrical propelled vehicle, a dynamo electric machine havingan armature, a series field winding and a shunt field winding, a sourceof electric energy, a multi-positioned controller having a neutralposition and a plurality of operating positions, said controller adaptedupon the initial movement thereof to connect said machine with saidsource, said controller being adopted upon further movement thereof toeffect acceleration of said machine, a reverse current relay associatedwith the terminals of said machine and responsive to the direction ofthe current in said armature, and means associated with said relayhaving an inoperative position when said machine is acting as a motor,said means being operable to maintain the initial connection effected bysaid controller when said machine is acting as a generator even thoughsaid controller has returned to said neutral position.

2. In an electrical propelled vehicle, a dynamoelectric machine havingan armature, a series field winding and a shunt field winding, a sourceof electrical energy, a multi-positioned controller having a neutralposition and a plurality of operating positions, said controller beingadapted upon operation thereof to connect the armature of said machineto said source and to efiect acceleration thereof, a reverse currentrelay associated with the terminals of said machine and responsive tothe direction of the current in said armature, and means associated withsaid relay having an inoperative position when said machine is acting asa motor, said means being operable to establish a circuit shunting saidarmature controller and thereby maintain a connection to said sourcewhile the machine is acting as a generator even though the controller isin a neutral position.

3. In an electrically propelled vehicle, a dynamo-electric machinehaving an armature, a source of electrical energy, a resistor associatedwith said armature, a multi-positioned controller adapted to, uponinitial operation thereof, connect said armature including said resistorto said source, said controller being adapted upon further operation toprogressively decrease said resistance and effect acceleration of saidmachine, a reverse current relay associated with the terminals of saidmachine and responsive to the direction of the current in said armature,and means associated with said relay having an inoperative position whensaid machine is actingas a motor, said means being operable to maintainsaid initial connections when the machine is acting as a generator onlywhen the total armature resistance has been cut out of said armaturecircuit.

4. In an electrically propelled vehicle a dynamo-electric machine havingan armature, a series field winding and a shunt field winding, a sourceof electrical energy, a multi-positioned controller having a neutralposition and a plurality of operating positions, said controller beingadapted upon operation thereof to connect said machine to said sourceand to effect acceleration thereof, a reverse current relay. associatedwith the terminals of said machine and responsive to the direction ofthe current in said armature, and means associated with said relayhaving an inoperative position when said machine is acting as a motor,said means being operable to maintain a circuit from said source throughsaid machine when said machine is acting as a generator even though thecontroller is in neutral position.

SYDNEY SLATER GUY. WILLIAM ARTHUR STEVENS.

